The present invention relates to a liquid crystal display device and a backlight thereof. More specifically, the present invention relates to preventing the deterioration of liquid crystal panel and preventing the generation of wrinkles on a sheet reflector while decreasing generations of a bright line and/or a black line.
A liquid crystal display device (LCD) has been widely used as a display for notebook computers and portable TVs among others. An LCD fundamentally includes a liquid crystal panel and a backlight applying a lamp light to the liquid crystal panel. The liquid crystal panel typically comprises an upper substrate, a lower substrate, and a liquid crystal layer between the two substrates.
FIG. 1 is a sectional view showing a position of a lamp of a conventional LCD device including a liquid crystal panel and a backlight. The liquid crystal panel 24 comprises an upper substrate 7, a lower substrate 6, a liquid crystal layer between the two substrates (not shown), an analyzer 8 adhered to an upper surface of the upper substrate 7 and a polarizer 5 adhered to a lower surface of the lower substrate 6.
The backlight comprises a light guide 3, a lamp 10 facing a side edge of the light guide 3, a lamp wire 21, a lamp housing 9, a sheet reflector 2 situated below the light guide 3, and a plurality optical films 4 adhered to an upper surface of the light guide 3. The lamp wire 21 supplies power to the lamp 10, and the lamp housing 9 protects the lamp 10 and directs the light therefrom to the light guide 3 through the side edge of the light guide.
The conventional LCD device also includes a pad 23, a main supporter 1, and a top case 22, which is connected to a side of the main supporter and an upper end of the liquid crystal panel 24. Pad 23 is situated between an upper surface of the upper end of the lamp housing 9 and the lower surface of the lower substrate to support the liquid crystal panel 24. The main supporter 1 shields the lower portion and the side of the backlight protects and supports the backlight. The top case 22 fixes the liquid crystal panel 24 to the main supporter 1.
The conventional LCD device has following problems.
First, after the construction, the edge of light guide 3 is placed between both upper and lower extensions of the lamp housing 9. To prevent wrinkles on the sheet reflector 2 with this construction, a gap must occur between the upper surface of the light guide 3 and the lower surface of the upper end of the lamp housing 9.
Normally, light from the lamp 10 is incident upon the side edge of the light guide 3 so that the light density, emitted through the upper surface of the liquid crystal display panel 24, is uniform over a wide region. However, the gap created by the above construction results in some of the light rays being reflected from the lamp housing 9 so as to be incident upon the upper surface of the light guide 3, as shown in FIG. 2. Thus, instead of the desired uniform light brightness, a bright line is created.
To counteract the bright line creation, a black color is printed on an area A of the sheet reflector 2. Unfortunately, if the print density is too great, then a black line is generated, and if the print density is too slight, then the bright line will still be generated.
Second, to prevent the bright line, the aperture of the lamp housing 9 can be made narrow. However, such narrowing of the opening causes the a portion of sheet reflector 2 above the lower extension of the lamp housing 9 to be pressed by the same lower extension. As a result, wrinkles are generated on the sheet reflector 2, especially at high temperatures.
Third, heat generated from the lamp 10 is transmitted to the liquid crystal panel 24 and thereby causing the liquid crystal to deteriorate.